PLATELETS FROM PATIENTS WITH BERNARD-SOULIER SYNDROME AND VON WILLEBRAND'S DISEASE

A B ST RA CT The antibiotic ristocetin only aggregates platelets in the presence of plasma von Willebrand factor. Platelets from patients with Bernard-Soulier syndrome do not aggregate upon addition of ristocetin although, in contrast to von Willebrand's disease, plasma levels of factor VIII complex (factor VIII clotting activity, von Willebrand factor activity, and von Willebrand antigen) are normal. The membrane surface of normal platelets was modified and compared to the surface of platelets from a patient with Bernard-Soulier syndrome in an attempt to identify the receptor involved in von Willebrand factorristocetin-induced aggregation. After the incubation of washed normal platelets with a preparation of ristocetin previously shown to contain a proteolytic contaminant, the aggregation response is significantly decreased on addition of normal plasma. Analysis by gel electrophore